[RESOLVED] How to improve this code?

[MrNorth]

Hi!

I have written a small method that keeps track of a pivot control containing months from jan-dec. The pivot can scroll both ways and I have to keep track of which way the scrolling occurs, and either reduce or increase the selecteddatetime by one month.

Here is the code so far

Private Sub CalculateSelectedDate(lastSelected As Integer, selectedPivotIndex As Integer)
	Dim diff = lastSelected - selectedPivotIndex

	' From feb-mar
	If diff < 0 AndAlso Math.Abs(diff) = 1 Then
		SelectedDate = SelectedDate.AddMonths(1)
	' From mar-feb
	ElseIf diff > 0 AndAlso Math.Abs(diff) = 1 Then
		SelectedDate = SelectedDate.AddMonths(-1)

	' From dec to jan
	ElseIf diff < 0 AndAlso Math.Abs(diff) > 1 Then
		SelectedDate = SelectedDate.AddMonths(-1)

	' From jan to dec
	ElseIf diff > 0 AndAlso Math.Abs(diff) > 1 Then
		SelectedDate = SelectedDate.AddMonths(1)
	End If
End Sub

I am almost certain this code can be written in a better way, and I am interested in knowing your opinions on how to refactor it?

What I check is

* which way the navigation is going by comparing last index and current index

* and two special cases for navigating between years

/Henrik

[SJWhiteley]

Why do you think it needs improving? What calculation do you think could be extracted out and performed only once?

[Grimfort]

If diff < 0 AndAlso Math.Abs(diff) = 1 Then 'That is the same as diff = -1
ElseIf diff > 0 AndAlso Math.Abs(diff) = 1 Then 'This is the same as 1
ElseIf diff < 0 AndAlso Math.Abs(diff) > 1 Then 'This is the same as <-1
ElseIf diff > 0 AndAlso Math.Abs(diff) > 1 Then 'And finally the same as >1

 Dim intMonths As Integer = 0
        Select Case lastSelected - selectedPivotIndex
            Case Is < -1, 1
                intMonths = -1
            Case Is > 1, -1
                intMonths = 1
        End Select
        SelectedDate = SelectedDate.AddMonths(intMonths)

Numerous ways to do that.

[MrNorth]

Thanks, I figured the code was overly complex!

/H